A compact (miniature) dual-optical module camera (also referred to as “dual-aperture camera”, “dual-lens camera” or simply “dual-camera”), as e.g. in a smart-phone, can be used in conjunction with appropriate computational photography algorithms for several purposes. These include achieving advanced digital zoom, lowering total module height while keeping high performance, improving low-light performance and creating depth maps. In order to simplify the computational photography algorithms and thus reduce time and errors, it is required that the two cameras be set as closely proximate as possible. In compact camera modules, the most ubiquitous form of achieving auto-focus (AF) and/or optical image stabilization (OIS) is by actuating (shifting) an imaging lens (or simply “lens”) module of the camera with respect to the camera sensor(s). The most common actuator type in such cameras is the voice coil motor (VCM). A VCM actuator includes coils, fixed (also referred to as “permanent” or “hard”) magnets and springs. When current is driven through a coil, an electro-magnetic (EM) Lorentz force is applied on it by the magnetic field of the magnets and the lens module changes position. The EM force is balanced against the springs to achieve the required position.
In dual-aperture photography, two camera modules enable taking two images of the same scene simultaneously. Each camera may include one or more VCM (or other magnetic) actuator(s) for AF and OIS purposes. When using VCM actuators, the VCM actuators are positioned in close proximity. The two camera modules may have identical or different optical elements (lens modules/lenses). Each VCM actuator needs then to actuate its respective lens module according to the optical demands. Each VCM actuator needs to operate separately, preferably as if it were not coupled magnetically to the other VCM actuator (i.e. as if it were a standalone module).
Two VCM actuators in close proximity may interfere with each other's magnetic field and may not work properly. This interference limits the minimal distance between the actuators and/or requires unique magnetic structures and changes to the VCM. A small distance is advantageous for minimizing camera footprint and for simplifying computational photography algorithms and calculations, because it results in smaller parallax.
Known solutions to the proximity problems posed by miniaturized dual-optical module cameras include use of off-the-shelf actuators and some means for magnetic shielding (see e.g. PCT patent application PCT/IB2014/062181). The latter limits the proximity achievable in the positioning of two actuators in a single camera. Another solution includes a VCM that houses two lenses that move together (see e.g. PCT patent application PCT/IB2014/062854).
There is therefore a need for, and it would be advantageous to have ways to construct a magnetically stable structure that can house two lens modules in close proximity to each other, and actuate each lens barrel in an independent way for AF purposes. In addition there is a need for an OIS mechanism coupled to such a structure.